Study On Vibration Of Multi-layer Structure Of Ballastless Track On High-speed Railway Bridge Under Moving Loads

Track bridge system dynamics is the research focus and hotspot in the field of railway engineering,especially in high-speed railway and heavy haul railway.The dynamic response limit of ballastless track structure on high-speed railway bridge is an important control factor for bridge design optimization.In order to study the vibration response of track bridge system,the train subsystem is regarded as a moving load.Based on the classical beam and plate theory,the dynamic response of track multi-layer structure is analyzed by analytical method and semi analytical method in the simplified model,and the vibration response law of track bridge system is revealed,which is of great significance to the dynamic design of ballastless track on the bridge.The main research work is as follows:Based on the classical slender beam theory,the dynamic model of ballastless track multi-layer beam structure on high-speed railway bridge under moving load is established.Through modal decomposition and other methods,considering the orthogonality of vibration mode and Schmidt orthogonalization,the dynamic response analysis method of track structure multi-layer beam system under moving load is proposed,the analytical solution is obtained,and the unified representation of track multi-layer beam structure vibration on the bridge is established,Some special boundary conditions are analyzed in detail.The common cases of multi-layer beam model of ballastless track on high-speed railway bridge,such as multi-layer simply supported beam,multi-layer cantilever beam and multi-layer free beam on rigid foundation,are solved.The correctness of the solution method proposed in this thesis is verified by comparing with other literature examples.Through the qualitative analysis of the vibration of the track multi-layer beam structure on the bridge,it can be seen that when considering the free vibration and stress vibration,the contribution of the higher-order modes to the overall vibration is small;The dynamic response deflection of the beam rail system at any position reaches the maximum when the load reaches the mid span;The interlayer stiffness affects the dynamic response of each layer of the track system under stress vibration by affecting the natural frequency of the structure.Based on the classical thin plate theory,the dynamic model of simply supported free supported(SFFS)double-layer plate under the moving load of ballastless track on high-speed railway bridge is established.Through the Levi solution and Fourier transform of thin plate,the dynamic response analysis method of ballastless track plate on high-speed railway bridge under the moving load is proposed.The vibration response of double-layer plate of ballastless track on high-speed railway bridge is solved via Newmark-β Methods.The effects of wheel rail gauge,eccentric load effect and Poisson’s ratio effect on structural vibration are analyzed by controlling variables.The difference of vibration response between SFFS track plate bridge double-layer plate structure and simply supported double-layer beam structure under moving load is studied.The results show that whether the rail layer effect is considered or not has little effect on the vibration of the track slab;When the wheel/rail gauge,small eccentric load and Poisson’s ratio are between 0 and 0.3,these factors have little influence on the vibration of the track plate structure,which can be ignored in the calculation.